Subscriber Discussion

How Would You Connect Network Switches For A Large 5 Building Video Surveillance System?

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Michael Silva
Aug 18, 2016
Silva Consultants

We are designing a video surveillance system for a large five-building office complex. Buildings are numbered 1, 2, 3, 4,and 5. Security monitoring station and VMS server will be in Building 3. Will be installing Cisco SG350-28MP Gigabit switches in each building. Plan to interconnect the five switches using fiber-optic cables between the uplink ports on each switch.

I have a question about how a system integrator would go about interconnecting these switches. Would you daisy-chain between switches (go from 1 to 2 to 3 to 4 to 5)?; or would you use a star configuration to the central switch (1 to 3, 2 to 3, 4 to 3, 5 to 3)? If using the first method, would you run a return loop from the first switch to the last switch (1 to 5) to provide redundancy? Or would you use a completely different method altogether?

I would love to get your opinion. Thanks.

U
Undisclosed #1
Aug 18, 2016
IPVMU Certified

Since all the data is bound for one destination, I think the star makes a lot of sense. The biggest drawback is that it may be a good deal more fiber, than a ring or bus topology. A lot depends on how centrally located building 3 is in relation to the other satellites.

The satellite switches are not dependent on each other to reach the SOC and no traffic is passed thru more than 2 switches.

A ring or redundant ring topology can make more sense when the resources accessed are distributed throughout the ring. When resources are distributed among all the locations, and accessed from any location, the central star becomes more of a gateway, essentially routing traffic between different ring nodes.

But you have the ideal case, since for the camera streams, the star (#3) is the always the destination, And for the viewing streams it's always the source, so it's very efficient.

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UM
Undisclosed Manufacturer #2
Aug 18, 2016

Star is the way to go. The core switch may want to be a beefier switch than the edge switches.

You don't want to have all of the data forced to flow through extra switches.

There are topologies such as ring to add redundancy, but that requires additional protocols running to prevent loops.

If you are worried about redundancy, you can run more than 1 fiber for each run, and then configure the switches for port trunking or failover in case a link goes down.

This is much simpler than a ring, and without the added delay and data pileup from a daisy chain.

UE
Undisclosed End User #3
Aug 18, 2016

Star topology usually works best. the main switch could be one of the newer 12 port SFP switches. i have a few sites with the Ubiquiti ES12F 12 Port 1G SFP switches as the aggregation point in the network. they just came out with the 16 X switch that is 16 10G SFP+ ports.

Ring networks can cause a lot of packet collisions if not properly configured. if you have to replace one switch down the road inevitably they will forget to provision it properly. your gigabit turns into a 1Mb connection since everything is colliding. look at it like a freeway running at 75 Mph with only one lane period and all the traffic is in the same lane trying to go both directions at once.

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Marc Pichaud
Aug 18, 2016

According to me, it depends...best is of course, a fiber star, and spaning but this costs more, especially when you have long distances, because you have a centralized convergent bandwidth: for recording and viewing .Network redundancy with Spaning tree (MST /RST) can be enable if each switch can support double bandwidth on their backlane during a link failure

There is a natural load balancing by spliting the bandwidth by network segments

With Ring topology, you will save a lot of wires/fibre compared with star topology and you get a natural spaning on two optical fibres but each switch backplane shall support the upcoming bandwidth from other switchs

so if you network between the 5 buildings is reaching for example 1,5 Gbit in total (stream 1 and 2 for rec & view) you could have to use a 10 mbits fiber backbone and pretty powerfull switchs.

In brief, Ring (so called daisy chain by you) is more competitive when the budget and the time are limited and for large distance. This is mostly use in industrial and urban deployments.

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Tyler Blake
Aug 18, 2016
BCI Integrated Solutions

Why aren't you just doing something like ubiquiti air fiber for this all to a central location? This would make a lot more sense and probably be a lot cheaper assuming you can access / mount on top of the buildings rather than trenching and having to run fiber.

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U
Undisclosed #1
Aug 19, 2016
IPVMU Certified

Do you need 5 radios or 9 with air fiber?

Also, the trench may already exist.

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Tyler Blake
Aug 19, 2016
BCI Integrated Solutions

Depends on how the buildings are located. If they are all in the Samek reaction from the central location you would only need 1 point to multipoint at the central and point to points at the smaller places.

Another alternative is using the smaller nanobeams that run off POE. They are super easy to set up and give 450mb of throughput. We install several every week at and have no issues with them and they take about an hour-hr1.5 to install each. Just run your cat6 wire and mount like a camera. There are pole and window mounts. Those you would need 10 total. And each one will eat a port on your switch, but they have 15km range and cost $90 ea roughly. By far the cheapest way to connect if it will get the job done for what you need.

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Marc Pichaud
Aug 19, 2016

Depends on distance and Wifi environement in this location.

450 Mbit theorical output and 15 km with a 100 m pole (!) might be written on the box keep in mind wireless isn't faul tolerant most of the time and have to deal with lots of parameters, including trees, wind, and all Wifi routers in the neighborhood between Tx/Rx

Real throughput shall be measured by real IT tools like Iperf, not with the one from ubiquity. Local test before any decision. Do we plan redundancy ? IN big installations it shall be considered. Not sure we can do it with Ubiquiti. Fluidmesh can have ring and routed solutions.

Latest point to consider with Wireless: do we plan Unicast or Multicast and how many PTZ do we have (sensitive to latency) If few PTZ , using UDp Unicast , wireless Unbiqui won't be a problem (wireless transmissions should be oversized to avoid latency)

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U
Undisclosed #1
Aug 19, 2016
IPVMU Certified

By far the cheapest way to connect if it will get the job done for what you need.

How long does that equipment typically last? Does it need periodic adjustments?

Fiber in conduit can last a long time without touching.

UE
Undisclosed End User #4
Aug 19, 2016

Depends of locations, how paranoid you are and available budget.

Star for sure, but if you are paranoid and and the switches has two uplinks, use the second unused port to connect all switches in ring as redundancy as well.

Don't make "false redundancy" and re-use the fibres to make the ring on-top the star, use separate fibre cables and different path for the ring.

Of course, choose switches that handles spanning tree / rapid spanning tree - without some logic to handle the paths, you will end up in big looping mess .. ;)

My 0.2$

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Michael Silva
Aug 22, 2016
Silva Consultants

My thanks to all for the great input - lots of good information here.

In the case of this particular project, it is new construction and we have the opportunity to easily get conduits for the fiber-optic cable between the buildings, and the cost of installing cable is insignificant compared to the overall project cost.

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